Multimedia

Play or download an MP3 of this story

When is a plant considered a weed? Experts at Penn State University have a simple answer: When the undesirable qualities outweigh the good qualities.

Consider the fact that crops generally produce several hundred seeds from each plant. By comparison, each weed plant can produce tens or even hundreds of thousands of seeds. And some buried seeds can survive up to forty years -- or even longer.

Eradicating weeds means that you have to remove all the seeds and roots so the plants will not grow back. But birds or the wind can reintroduce them to the land.

A more common way to deal with weeds is to control them enough so that the land can be used for planting. Experts advise using two or more control methods to deal with weeds.

Chemical weed killers or natural treatments like corn gluten can suppress weed growth. Dense planting of a crop can also act as a natural control.

Bill Curran is a professor of weed science at Penn State, in University Park, Pennsylvania. He says one of the most common methods for suppressing weeds is dense planting.

He says a dense, competitive crop that quickly shades the soil will help suppress many weeds. The seeds need light to grow, so blocking the sun will reduce weed growth.

Other controls include turning over the soil, pulling the weeds or covering them with mulch made of shredded wood, garden waste or other material.

But even mulch has its limits. Natural resource specialists point out that weeds can be transported in mulch. This is also true of soil, grain, hay and animals.

Yet animals like sheep or goats eat weeds, so they can provide a biological control. Insects and other organisms can also act as biological controls.

Preventing the spread of weeds is an important part of weed management. Farm vehicles should be kept out of areas with weeds. If that is not possible, then clean off the equipment and your shoes when leaving.

Some people burn weeds or bury them deeply or make them into mulch.

Professor Curran says another way to make use of weeds is to compost them. Heat is produced in the process of making organically rich compost to improve soil. The heat will kill many, though not all, weed seeds. The same is true for seeds that pass through animals that graze on weeds.

Report

Reason *

Please enter the code shown on the image

"I love sitting in traffic!" said nobody ... ever. We all hate traffic. If you want to complain about traffic in English, this article will help. And you can find out if your city made the Top Ten List for Worst Traffic. Also, find out which cities have the fastest moving traffic on the planet. More

Jakarta has the worst traffic in the world, according to a recent study. So, the city is building a huge mass transit system to help people in Jakarta get from Point A to Point B more quickly and easily. But this requires sacrifice because the construction of the system is causing more traffic. More

UN Secretary-General Ban Ki-moon asked for a study on peacekeeping operations. The study gives suggestions to improve United Nations peacekeeping operations around the world. It deals with the responsibility of the peacekeepers, their orders, and what people expect of them. More

Also, Kerry called for investigation in Nemtsov's death and defended Israel at the UN. Iraqi forces have launched an offensive against Islamic State fighters. And, North Korean has fired missiles into the sea in an apparent protest against joint U.S. and South Korean exercises. More

A new report says North Korea could have as many as 100 nuclear weapons by 2020. That includes the 16 to 20 such weapons the report’s writer says the closed country already has. Not everyone agrees North Korea will be able to build that many more nuclear weapons in the next five years. More

Mitochondrial Replacement Therapy uses the genetic material from three people to create babies. The stated purpose of the therapy is to help mothers avoid passing genetic mutations to their babies. Some say MRT will lead to 'designer babies.' Others say it is dangerous, immoral or just wrong. More

Most scientists agree that increasing amounts of carbon-dioxide gas in the atmosphere is partly to blame for climate change. Climate change can have a big effect on weather conditions around the world. Scientists are looking for the best and least costly methods for capturing the gas. More

U.S. officials say birth rates for unmarried women over age 40 have been rising in recent years. In fact, the rate in 2012 was almost 30 percent higher than just five years earlier. There are single mothers by choice. They are generally older, successful, well-educated, and financially secure. More

Branden Jacobs-Jenkins' latest play 'An Octoroon,' is showing at a theater in New York City. It is based on a 19th Century work by Dion Boucicault. It tells about a white man who falls in love with a woman who is part black. At the time, mixed race marriage was banned in southern US states. More

A common battle cry of teenagers to adults is, "You just don't understand me!" Well, they might be right. A brain scientist (neuroscientist) and mother to two teenagers says the teenage brain is quite different from the adult brain. She "debunks," or clears up three common myths about teenagers. More